In a large skillet, cook sausage and onion over medium heat until meat is no longer pink; drain. Transfer to a large bowl. Stir in the spinach, cream cheese and egg. Add 1 cup mozzarella cheese, cheddar cheese, cottage cheese, Parmesan cheese, salt, pepper and, if desired, cinnamon. , Stuff pasta shells with sausage mixture. Arrange in 2 shallow 2-qt. or 11x7-in. baking dishes coated with cooking spray. Combine the sauce ingredients; spoon over shells. , Cover and bake at 350° for 45 minutes. Uncover; sprinkle with remaining mozzarella. Bake until bubbly and cheese is melted, 5-10 minutes longer. Let stand for 5 minutes before serving.